This invention relates to butterfly valves designed for clamping between flanges in a pipeline, typically in an oil field, and is an improvement on the butterfly valve shown in U.S. Pat. No. 3,498,584. Experience in the field with construction and operation of the prior valve has given rise to a need for improvement in design and operation, and it is an object of the present invention to provide such a new and improved butterfly valve.
Some of the problems are excessive wear of the valve disk, alignment problems of valve parts when the valve is disassembled for replacing a valve seat, operator error in opening, closing and setting the valve, accomodation of both manual and remote control devices, and clogging of the fluid injection system.
Other objects, advantages, features and results will more fully appear in the course of the following description.